Field of Invention
The present invention relates to the field of signal processing, and more particularly to a signal processing circuit and method with a pressure-sensitive sensor array.
Description of Related Arts
The pressure-sensitive sensor is adapted for converting the externally applied pressure into electrical signals. It comprises resistive pressure-sensitive sensor, capacitive pressure-sensitive sensor and piezoelectric pressure-sensitive sensor. The resistive sensor is made from early metal sheet electric resistance strain gauges to existing composite materials and nano-materials (graphene). Correspondingly, the size becomes smaller and smaller. Therefore, the scope of application of the pressure-sensitive sensor is gradually expanded.
For example, the touch key, comprising the conventional pressure-sensitive sensor made from composite materials, is applied to household electrical appliances and other fields, for replacing traditional mechanical key. It has some advantages such as long service life, good looking appearance, and multiple functions able to be realized. Generally, in order to obtain excellent signal quality, the pressure-sensitive sensor is in a bridge form on electrical properties, so as to convert the pressure signal to the differentially electrical signal. However, every bridge has a corresponding differential signal pair, so that for manufacturing a large press key array, connection wires of the signals become more. For example, the 4×3 keyboard has 24 signal wires and 2 excitation signals, so that the wire area is increased, which makes against reducing the product size, reduces reliability, and simultaneously needs subsequent signal processing chips to increase input channels, thereby increasing manufacturing cost.
For example, Chinese Patent CN 200710087168.0 disclosed a method for constructing a fingerprint image input apparatus through a pressure-sensitive sensor, which comprises steps of: firstly respectively horizontally and vertically arranging multiple pressure-sensitive sensors, whose contact surface maximum radius is less than fingerprint single gully width, on an insulation board whose area is larger than a singer area, obtaining an array formed by the multiple pressure-sensitive sensors, wherein: every sensor produces a strongly electrical signal while being trigger by pressure, the sensors without pressure do not produce electrical signals; when a finger is placed on the sensor array, the protruding part of the finger fingerprint will trigger the sensor, the sensor produces the strongly electrical signals. Because every sensor in the sensor array represents one pixel point in a fingerprint image, the strong and weak signals produced by the sensor array form a binaryzation fingerprint image. In spite of resolving problems through the pressure-sensitive sensor array, the method do not treat the signal connection wires, so that the signal connection wires adopted by the pressure-sensitive sensor array are still more, thus the wire area is larger, which makes against reducing production size and simultaneously decreasing reliability of the wires, and increasing manufacturing cost.